Separation of solid constituents from oils containing the same



Patented Jan. 17, 1939 PATENT OFFICE",

SEPARATION or soup CONSTITUENTS FROM OILS CONTAINING THE SAME Mathias Pier and AngnstElsenhnt, Heidelberg,

Germany, assignors to Standard-I. G. Company, Linden, N. 3., a corporation of Delaware No Drawing. Application November 8, 1935, Serial No. 48,868. In Germany November 9 1 Claim;

The present invention relates to the separation of solid inorganic and/or organic constituents from oils containing the same.

It has already been proposed to flocculate out solid constituents from oils containing the same by the addition of hydrocarbons rich in hydrogen, such as propane, butane or the like. In this manner, however, not only inorganic solid constituents but also large amounts of asphalt are flocculated out if the said oils contain asphalt; this is undesirable for example if the said oils are to be subjected to a subsequent destructive hydrogenation inthe liquid phase because the yield of valuable products is reduced. In this case it is preferable to remove only the inorganic solid constituents and eventually the hardest constituents of asphalt and other solid substances which it is dlillcult to convert by destructive hydrogenation.

We have now found that the said undesirable removal of large amounts of asphalt can be avoided by treating the initial materials, 1. e.,

oily substances contaminated with inorganic solid constituents and/or with hard asphalts and/or with other solid substances which it is dimcult or impossible to convert by destructive hydrogenation, with saturated, in particular aliphatic, hydrocarbons of low boiling point consisting mainly of hydrocarbons having from about six to ten carbon atoms in the molecule at elevated temperatures, preferably between about 170 C. and somewhat above the critical temperature of the said aliphatic hydrocarbons and more particularly in the neighborhood of the critical temperature of these hydrocarbons, i. e., at between about 50 degrees centigrade below and about 20 degrees centigrade above the said critical temperature (the said hydrocarbons being hereinafter sipmly referred to as the solvent" since the bulk of the initial materials is dissolved by them), the two layers formed, consisting of solid residue, asphalt and a little solvent on the one hand and asphaltic oil and solvent on the other hand, being separated from each other at elevated temperature.

As initial materials may be mentioned mainly tars or hydrogenation residues of coals, tars or asphalt-basic crude oils. These are mixed for example with an equal amount, double the amount or a multiple of the amount of hexane, cychlohexane, methylcyclopentane, heptane, octane or mixtures of the same and heated to elevated temperatures, as for example above 170 C. in a closed vessel. It is preferable to select a temperature which lies from 10 to 50 below the solvent may or in counter-current to the initial materials the critical temperature of the solvent employed. It is also possible, however, to carry out the treatment at a temperature slightly above the critical temperature of the solvent. The period during which the solvent is allowed to act on the initial material should preferably amount to more than five seconds. For continuous working be led in'the same direction as The treatment may also be carried out in several stages. For example the initial materials may be brought into contact with difierent solvents. Furthermore the conditions as regards temperature and pressure may be varied in the different stages. For example the treatment in the first stage may be carried out at higher or lower temperatures than in the following stages. In the single stages, the pressure used may be the pressure which is spontaneously produced or a higher pressure which is produced by the addition of a gas, as for example nitrogen or methane or hydrogen. The pressure should be so high that at the temperature employed the solvent is present in the liquid state or that, for example when working at a. temperature above the critical temperature of the solvent, at least the bulk of the solvent is dissolved in the initial oil so that only the inorganic solid substances are precipitated from this oil. As a rule pressures of at least 5 atmospheres are employed, but preferably the pressures are considerably above this value. 1

It is especially advantageous to carry out the treatment in the presence of solvents for asphalts and other carbonaceous substances of high molecular weight. Heavy oils poor in hydrogen, for example, such as anthracene oil or aromatic oils, as for example those obtained by destrucive hydrogenation of mineral coal are suitable for: this purpose. The oil freed from the solid substances may then be subjected, suitably after removal of the solvent used for the separation, to a treatment with hydrogenating gases, such destructive hydrogenation.

If the solvent employed consists of a mixture of two or more different hydrocarbons we understand by the critical temperature of the solvent a temperature which lies between the critical temperatures of the single components and which depending on the proportions of these components in the said mixture is nearer to the critical temperature of the one or other component.

By working in this manner it is possible to split up the initial material into an asphaltcontaining oil of great purity and a solid substance which only contains small amounts of substances soluble in benzene. The process has the further advantage that the separation oi the solid substances may be carried out by sedimentation, although other methods of separation may be employed, if desired.

In order to carry out the process, the oil or the oily residue is treated in a pressure-tight vessel and then the oil solution is transferred by siphon action -or by additional pressure into a second pressure-tight vessel in which the recovery or the solvent is effected mainly by releasing the pressure, while the remainder of the solvent is recovered by the addition of steam at elevated temperature. In this way there is practically no waste of extraction agent.

The solid undissolved constituents, which are also freed from solvent by means of steam, may be mechanically removed from the pressure-tight vessel.

The following example will further illustrate the nature of this invention but the invention is not restricted to this example. The parts are by weight.

Example 150 parts of an oil-containing residue containing per cent of constituents insoluble in benzene obtained by the destructive hydrogenation of mineral coal are mixed in the ratio of 1:1 with a heavy oil boiling above 325 0. derived from the same coal. To 1 part of the said mixture there is then added 0.75 part of a mixture of heptane and hexane or of a corresponding paraiiinlc benzine fraction. The whole is heated to 270 C. whereby a pressure of from 20 to 25 atmospheres is produced. The mixture is stirred for some time at the said temperature. Arte; allowing to settle for an hour; the heptane-hex ane solution is drawn ofl and the mixture of heptane and hexane separated from oil by distillation, from about to per cent of the total oil with about 1 per cent of constituents insoluble in benzene being thus obtained. The undissolved portion remaining in the reaction vessel is freed from solvent by means of steam and the remaining solid crumbly substance is removed from the reaction vessel' without any difliculty by means or a worm. The undissolved portion only contains about 20 per cent of constituents soluble in benzene.

What we claim is:

A method of treating charging oil for adestructive hydrogenating process to remove objectionable solid material unsusceptible to destructive hydrogenation which comprises mixing said charging oil with a hydrocarbon solvent containing between 8 and 10 carbon atoms to the molecule, adding to said oil solvent mixture a heavy oil having a low hydrogen content capable of dissolving high molecular weight carbonaceous material, subjecting said mixture to a temperature near the critical temperature of the hydrocarbon solvent and to a pressure in excess of 5 atmospheres and suflicient to prevent separation of said solvent and charging oil, maintaining said oil solvent mixture at said temperature and pressure for a period adequate to precipitate said objectionable solid material from said oil, removing the precipitate so formed and separating the solvent from the remainder of said oil.

MA'I'HIAS PIER. AUGUST EISENHUT. 

